Field of the Invention
The present invention relates to a voltage conversion device capable of stepping up a voltage supplied from a battery and supplying the voltage to a load.
Description of the Related Art
Conventionally, there has been known a load-driving device for stepping up a battery voltage using a step-up circuit to supply the voltage to a load (for example, a motor). Such a load-driving device is mounted on, for example, electricity-powered vehicles, such as hybrid automobiles and electric automobiles (including fuel-cell vehicles).
In this connection, Japanese Patent Laid-Open Publication No. 2006-288163 describes a technique of determining which voltage sensor is abnormal in a load-driving circuit including a battery, a step-up circuit, a battery voltage sensor for detecting a battery voltage, an input voltage sensor for detecting the input voltage of the step-up circuit, and an output voltage sensor for detecting the output voltage of the step-up circuit by comparing three voltage values detected by the sensors.
In the technique described in the abovementioned patent document, an abnormality determination is made on each sensor on the basis of the differences among the voltage values detected by the respective sensors, taking advantage of the idea that ideally, the three voltage values are equalized when having stopped step-up operation by the step-up circuit.
In the technique described in the abovementioned patent document, however, the step-up (or boosting) operation of the step-up circuit needs to be stopped when a determination is made to discriminate among the respective voltage sensors for abnormality. Accordingly, the technique is problematic in that a load being driven by the output voltage of the step-up circuit degrades in power performance due to the stoppage of step-up operation for the purpose of sensor abnormality determination.
It is an object of the present invention to provide a voltage conversion device capable of discriminating between the battery voltage sensor and the input voltage sensor of a step-up circuit for abnormality, without stopping the step-up operation of the step-up circuit.